Quicker tab stacking

It is already possible to tile/untile vertically and horizontally using hotkeys or the omnibar, but it is not I think possible to make stacks, manipulate stacks or delete stacks.

If I have two tabs open in one stack, and open a new tab, I need to drag it onto the existing stack. A hotkey to add to stack, or as a part of the vivaldi bar would be nice. Maybe the latter option since it would require "add to stack" and "choose stack" feature if you have more than one stack.

In addition, it would be nice to be able to have a split view (stack tiled vertically) with tabs in each split. Would be more similar to having two windows side-by-side - but one window tiled uses more of the screen making it preferrable to me at least.